Method of forming a pipe covering



March 6, 1962 T. KENNEDY METHOD OF FORMING A PIPE COVERING Filed Aug. 25, 1958 INVENTOR.

7'50 KEN/V60 Y IQTTOAP/VEVS 3,024,153 METHOD OF FORMING A PIPE COVERING Ted Kennedy, 715 Forest Ave, Ann Arbor, Mich. Filed Aug. 25, 1958, $811. No. 757,007 2 Claims. ((31. 156-187) The present invention relates to improved coverings for pipes, conduits, and like structures installed underground, hence subject to corrosive attack or other deteriorative action by conditions or elements present in the soil, and to a method of forming the covering. A wrapped cover of substantial body is produced by which the pipe is shielded against the mentioned effects, as well as given improved mechanical protection for the pipe, both after installation and in handling prior to installation.

An object of the invention is to provide an improved protective pipe covering of this sort, in which a flexible carrier board or wrapping core of paper, fiber, asbestos, or like thermally insulating material is employed as the basic wrapper component of the covering. This core or carrier board has a protective plastic film applied to both sides thereof and extending beyond its opposite edges. The film, in accordance with another aspect of the invention, may be a heat scalable one to provide Well fused zones at the wrapped joints, but in any event it serves as a sea-ling agent protecting the fibrous material of the board at its sides and edges against contact and attack by soil moisture, chemicals, fungus, as Well as by oil or other fluid carried by the pipe.

Another object is to provide a method of forming a covering as described which has an external overcoating layer applied thereover in a heated flowable, molten condition. This hot coating causes the overlapped and film coated edges of the wrapped carrier core or board to fuse or become tacky and heat seal together at the seam, sealing the carrier board very effectively at its joints.

A further object is to provide a protective pipe covering which has considerably increased stiffness, strength and body, due to the fibrous nature of the carrier core or board; and thus is enabled to better Withstand the elevated temperature of application of the external overcoating.

A still further object is to provide a pipe covering, and method of producing the same in which, with or without a molten overcoat applied as described, the layers of plastic film. coating the sides of the carrier board still have direct contact to shield the board against deterioration or absorption of moisture at the lap.

Another object is to provide an improved film coated wrapping material of improved body for the foregoing ends.

The foregoing as well as other objects will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawing illustrating preferred embodiments of the invention, wherein:

FIG. 1 is a fragmentary View in side elevation, partially broken away, showing a pipe equipped with the improved wrapped and overcoated covering of the invention;

FIGS. 2 and 3 are, respectively, views in enlarged scale and in section along lines 22 and 3-3 of FIG. 1; and

FIG. 4 is a fragmentary perspective view showing a pipe with a carrier board wrapping according to the invention partially applied thereto, indicating approximately the relative thickness of the carrier board.

The reference numeral generally designates a pipe, conduit, or like elongated object such as a cable, etc., which is to be installed inthe ground. The numeral 12 designates the cover of the invention to protect pipe 10 atent against attack and deterioration as the result of various conditions, phenomena or elements of the soil in which the pipe is buried. The reference numeral 14 denotes a coating compound applied to the pipe, which may be of a known bituminous type, or a rust inhibitive petroleum Such waxes are well known in the art, possessing excellent corrosion resisting qualities and being readily applied to a length of pipe. As preferred herein, the waxes available to the trade have a softening point in the neighborhood of F. and are applied to the pipe 10 at temperatures in the range of approximately 250 F. and 350 F.

In accordance vw'th the invention the covering 12 basically comprises a wrapper 16 of a flexible carrier board of paper, fiber, asbestos or other fibrous material, in a relatively thick gauge, having thermal insulating properties. It is shown in the form of an endless web of considerable width and substantial thickness. Moreover, in accordance with the invention, the entirety of its surface, including its inner and outer sides and edges, is encased in a suitable heat scalable plastic film or coating 18 which extends beyond and around each of the edges. Plastics suitable for the purpose are polyethylene, polyvinylchloride, nylon, etc.

The thus coated board is applied by spiral or longitudinal winding to the pipe 10, preferably pre-coated with the bituminous or wax layer 14, and an external overcoating 20 of a similar bituminous or wax compound is then applied in a hot or molten state, in excess of the melting point temperature of the plastic film or coating 18. This causes the plastic coatings to fuse and seal to one another at the zones 22 of seaming or overlap. The overcoat 20 is applied at the time of application of the carrier board 16 and a very effective seal is had.

Even in the even that no overcoat 20 is applied, the plastic film coatings 18 of the carrier board 16 remain in contact at the seam, and in contact with the undercoating 14 if one is employed, so that no material is exposed at the lap which will deteriorate or absorb moisture.

A pipe covering is thus provided which has a thickness sufficient to impart substantial stiffness and rigidity to make it an effective mechanical shield along the length of the pipe, well protected during handling and installation. This type of fibrous wrapper will withstand relatively high temperatures of application to the hot molten coatings 14 or 20, without destructive melting of plastic. As indicated above, various types of synthetic plastic coatings 18 for the wrapper 16 are suitable, provided, of course, they are capable of heat sealing, when this procedure is desired. In any event, there is preferably a substantial width of the plastic film overextending the opposite edges of carrier board 16 to insure protection in these seam zones.

The invention affords considerable latitude in regard to the procedure of applying the covering or wrapper. As indicated above, it may be applied to a bare pipe or to one provided with an undercoating 18 and, moreover, while such undercoat is at a temperature either above or below the fusing point of the material of the plastic film of the wrapper. Accordingly, the completion of the covering may be expedited and facilitated by applying the external coating, at a film-fusing temperature of the latter, just as soon as the covering 12 is wrapped on pipe 10, whether the latter is bare or cold or hot undercoated.

What I claim as my invention is:

1. The method of protecting conduit from corrosion which comprises cover-ing the conduit with a flexible, corrosion-resistant sheet having opposite surfaces and edges of a synthetic resinous plastic material which becomes sufliciently tacky to heat seal when heated to an elevated temperature, such covering step being percontinuous overlapped seam to provide said overlapping folds.

References Cited in the file of this patent UNITED STATES PATENTS Putman Feb. 20, Holtz Sept. 15, Duggan Dec. 22, Converse Oct. 10, Bennett Apr. 24, Hopkins Apr. 1, 

1. THE METHOD OF PROTECTING CONDUIT FROM CORROSION WHICH COMPRISES COVERING THE CONDUIT WITH A FLEXIBLE, CORROSION-RESISTANT SHEET HAVING OPPOSITE SURFACES AND EDGES OF A SYNTHETIC RESINOUS PLASTIC MATERIAL WHICH BECOMES SUFFICIENTLY TACKY TO HEAT SEAL WHEN HEATED TO AN ELEVATED TEMPERATURE, SUCH COVERING STEP BEING PERFORMED BY WRAPPING THE SHEET AROUND THE CONDUIT IN OVERLAPPING FOLDS, APPLYING OVER TTHE THUS WRAPPED SHEET A COATING OF A HEAT-SOFTENABLE, CORROSION-RESISTANT COMPOUND AT A TEMPERATURE NOT LESS THAN THE HEAT-SEALING TEMPERATURE OF THE PLASTIC MATERIAL, AND HEAT SEALING THE OVERLAPPING FOLDS OF THE SHEET TOGETHER BY THE HEAT OF THE COATING. 